1. Field of the Invention
The present invention generally relates to a workpiece holding system utilizing an improved vise having jaws that remain parallel with the workpiece and introduce a downward force on the workpiece to retain it against a precision supporting surface with the system of this invention primarily intended for use in holding workpieces on EDM wire machines. Each jaw has a step at the bottom which is significant when used on a wire EDM machine as it provides the ability to "pick up" the location of the workpiece from four sides. The system includes a dovetail incorporated into the vise with the position of the dovetail being the same regardless of the size of the vise thereby making it possible to use two different vises in a vertical setup to hold elongated workpieces accurately and making it easy to change from one vise to another. A single adjustment block can be used for a number of vises thus reducing the overall cost of the system. The jaws are inclined towards the top providing the ability to spring under pressure to force the workpiece downwardly but once the jaws are parallel with the workpiece, they will not bend any further even under increased pressure thereby holding the workpiece more firmly and accurately. A vertical dovetail adapter has been provided to support more than one vise of different size or the same size and an adjustment block has been provided which has a male dovetail for quick attachment of vises, vertical dovetail adapters and the like.
2. Description of the Prior Art
Various efforts have been made to accurately support workpieces when work operations are being performed on the workpieces. Such devices include clamps or vises adjustably supported on a table or other support structure and which include at least one movable jaw to grip the workpiece. The relatively movable jaws are provided with structural features which convert a portion of the clamping force to a downward force exerted on the workpiece to move the workpiece downwardly into firm contacting relation to a precision bottom surface thereby accurately and firmly supporting the workpiece in desired location. The following patents relate to this field of endeavor:
______________________________________ 1,454,993 3,514,092 2,373,384 3,791,640 2,806,411 4,240,621 2,861,492 4,411,415 3,089,708 4,518,155 3,232,602 European Pat. 0 052 379 3,416,784 ______________________________________
While the above patents include structures for exerting downward force on the workpiece when the workpiece is clamped by the opposing jaws of a vise, none of them disclose the specific structure of the jaws used on the vise of the present invention and none of them disclose the overall system of this invention including the dovetail arrangements, the vertical adapter, adjustment block and related components.